FIGS. 8-10 of U.S. Re. Pat. No. 28,990 illustrate the fetal electrode most commonly used in the United States today. The product comprises a curved form sustaining guide tube through which an electrode assembly can be delivered to a fetal presenting part (typically the scalp) during delivery. The electrode which engages the fetus is a coil that extends from the forward end of an electrode holder and can be rotated by means of a flexible drive tube passing through the guide tube and adapted to engage a plate-like maternal electrode extending from the rear of the plastic holder.
The device illustrated in the '990 reissue patent has acquired substantial commercial success. The present invention provides an improvement over the guide tube of the '990 reissue patent. Specifically, a guide tube in accordance with the invention helps to ensure proper electrode attachment and is easier to use with an irregularly shaped cervix which may not be readily accommodated by the fixed curve of the guide tube of the '990 reissue patent.